A language for wireless sensor webs called the Sensor Web Language (SWL) is presented. SWL is especially useful for transmitting information over low-power wireless networks with relatively low bandwidth. The language has been designed for automated translation into three software layers. SWL compilers translate SWL statements into server, browser, gateway and sensor node software components of a wireless sensor web. Our approach provides flexibility and efficiency to wireless sensor web developers. Sensor webs can be readily deployed or modified (e.g. adding new sensors, recalibrating sensors) by a straightforward recompilation of the SWL statements. A prototype wireless sensor web for environmental applications that uses SWL is discussed in the paper. An example SWL program is presented that describes a sensor web with a cellular telephone gateway, two sensor nodes, four sensors and a Linux server base station.